This invention relates to a method and a system for redistributing fuser oil from areas of high fuser oil concentration on a fuser surface to provide more uniform fuser oil distribution on the fuser surface.
Electrophotographic copier/duplicator machines typically use dry toner to create an image on paper. The dry toner is transferred to the paper in a transfer subsystem and permanently fixed to the paper with heat and pressure in a fusing system. The fusing system is typically composed of a heated fuser roller, a heated or unheated pressure roller and an oiler (wick roller) for applying a release fluid (fuser oil). Alternatively a fuser belt system may be used. Both systems require the use of a wick roller to apply oil to the fuser surface. The fuser oil is typically uniformly applied across the fuser surface where toner will come in contact with the fuser surface. Since copier/duplicator machines run various paper widths and image directions, the fuser oil is required to be applied to the fuser surface over at least a length as long as the widest paper to be fused. When large quantities of narrower paper are run this can cause excessive fuser oil problems on the outer portions of fuser surface. This problem is particularly acute in copier/duplicator machines where a range of wide and narrow paper is used with predominately the narrower paper being used. When running the narrower paper, oil is still applied to the ends of the fuser surface outside the paper edges. This oil will continue to accumulate until it may run off the fuser surface, evaporate or be taken away with the wider sheets when they are run. The excess oil delivered to the fuser surface can cause various problems. For instance oil running off the fuser surface will contaminate the copier/duplicator machine and possibly stain a customer""s floor or the like. Oil evaporation results in oil vapor which may come in contact with the corona charger thereby reducing the life of the corona charger by depositing silicone onto the corona charger wires thus reducing the charger uniformity. Excess oil taken away on the copy can cause oil staining on colored paper, reduce the ability to write on copies with a ball point pen and possibly result in the transfer of excess oil to the photoconductor film which will cause image generation defects and the excess oil may reduce paper drive roller friction thus effecting the paper handling performance. Clearly the presence of the excessive oil on the outer ends of the fuser surface is very undesirable.
Previous solutions to this problem have been to supply the customer or user of the copier/duplicator machine with custom size wick rollers for specific paper sizes. This is not easily done with copier/duplicator machines where multiple paper widths can be loaded into the same machine for selection by the user. The use of a plurality of wick rollers in such machines is not feasible.
Accordingly, a continuing search has been directed to the development of methods for supplying fuser oil to the fuser surface in the required quantities while avoiding the build up of fuser oil on the outer ends on the fuser surface when large numbers of narrower copies are run.
It has now been found that the accumulation of oil on the outer ends of the fuser surface can be avoided and more uniform fuser oil distribution on a fuser surface is achieved by positioning a fuser oil redistribution roller in interactive contact with at least one of the fuser surface and a heater roller in interactive contact with the fuser surface, the redistribution roller consisting essentially of a porous material body covered along its length in contact with the fuser surface or at least one heater roller with a compliant oil transfer material.
The invention further comprises a fuser system having more uniform fuser oil distribution comprising: a fuser surface; a pressure roller positioned to engage paper bearing a toner image between the fuser surface and the pressure roller; a wick roller positioned to engage the fuser surface and apply a selected quantity; of fuser oil to the fuser surface ahead of engagement of the paper by the fuser surface; and, a fuser oil redistribution roller positioned to interactively engage at least one of the fuser surface after the fuser surface has engaged the paper and at least one heater roller in interactive contact with the fuser surface.